A public todo list has been requested before but I don't want to publish it for a couple of reasons... it often changes at the last minute, things are randomly re-prioritised due to things behind the scenes, and everyone's got their pet feature they want to see developed first and I'm worried there will be a lot of "nagging" (or at least prompting from users) to see their favourite feature bumped up the list or completed.
It's also difficult to take new feature suggestions because we already have so much on the todo list - we might not be able to get round to them for a long time. Thanks for the ideas and I don't want to tell people to stop being creative, but please be aware that last time I counted there were already 100 things on the list! So we generally try to do things the most number of people have asked for, or will benefit the largest portion of C2 users. Watch out for the "what's next?" polls we occasionally run.
There are a few other technical issues as well: anything to do with CocoonJS likely has to be done by Ludei, not Scirra, but I know they are actively working on publishing solutions and improvements for Construct 2 as we speak.
WebGL shaders is another tricky one: I personally would love to implement it because it's awesomely cool. However it's a significant amount of work, and ultimately it would not reach many users. Remember IE does not support WebGL, basically only Chrome and Firefox do - and then anyone with old graphics card drivers gets WebGL switched off as well. WebGL is hardly supported on mobile at all, and we have found unlike on desktop WebGL actually renders slower than canvas 2D, so switching on shaders to use effects will cause a big drop in performance before you've even shown an effect... overall, only about 1 in 4 desktop users would be likely to see the effects. Given the large amount of work it is, I think it would be best to postpone it for the time being. I'm sure support will be better in future.
Other suggestions often have similar complications behind the scenes. Often it seems simple but in actual fact there are a great deal of factors to take in to account.